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Commissioned Reports - Adding Value


Date: 2007
Title: The Manual – adding value to home-grown timber (CV0730)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
The production of an 'adding value to home grown solid timber' manual. A review of the opportunities to add value to timber from the earlier stages of scanning and sorting through to wood modification. Published jointly with Scottish Enterprise and made freely available.

This manual aims to communicate some of the opportunities available for adding value to UK sawn timber. It presents a wide breadth of opportunities, illustrated using results from previous and current research and practical experience, as well as providing a directory for finding further information to assist in future decision making.


Date: 2007
Title: Scoping Study - Scaffold Boards (231951)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This scoping study addressed the technical potential and possible challenges in manufacturing laminated scaffold boards from Sitka spruce falling boards so that they meet the performance requirements of BS 2482:1981 - (specification for timber scaffold boards).

Currently Sitka spruce is not a timber included in BS 2482 as being suitable for use as scaffold boards, though this standard relates to scaffold boards from solid timber and does not consider laminated material. A BRE project has been configured on four main points:

1. Most appropriate lay-up of the laminated scaffold boards
2. Technical performance
3. Investigation of the development of compression creasing in laminated Sitka spruce scaffold
    boards
4. Service life durability


Date: 2007
Title: Development of UK grown timber for industrial applications (BRE Digest 503)
Authors: Report commissioned from BRE
Full Report: BRE Digest 503 available from www.brebookshop.co.uk

Summary
A major output of this work was BRE Digest 503 “External timber structures – preservative treatment and durability”, in collaboration with the Wood Protection Association.  Two processes to potentially enhance durability processes for timber elements such as piling, poles and bridge beams were investigated: pre-installation of borate preservative via centre borings and polymer wrapping.


Date: 2006
Title: Scoping Study - English Hardwoods (231950)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This scoping study investigated the potential for re-engineering small diameter and coppiced grown English hardwoods as value end products. In principle, hardwoods of any dimension can be utilised, although the cost benefits are greatest with under utilized small dimension material. Whilst the range of products is limited only by the imagination, the equipment and approach to re-engineering is basically the same, regardless of end use or application. However, for certain end uses the manufacturer will need information relating to the timbers performance and properties.

There are two approaches that can be taken:

1. Re-engineering by conventional gluing of dry timber
2. Re-engineering by green gluing, with the moisture content at or above fibre saturation point

Re-engineering by conventional gluing has the advantage of being inline with the current regulatory requirements for the structural codes and standards and may prove a more economical route to bring products to market. However, gluing in the green condition offers potential to build in stability and processing advantages, which may prove beneficial.


Date: 2005
Title: Increasing the density of UK grown timber by cellulose addition (222189)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This project looked at the opportunity to increase the density of UK grown timber using a process similar to the Indurite technology. The curing process, as used at BRE on the advice of Indurite, may not have been fully optimised and with a fully optimised curing process it is possible that better results for the range of tests carried out may have been achievable. But based on results that it was possible to achieve it can be said that the Indurite process shows considerable promise and with full optimisation can yield significant improvements to a range of mechanical and physical properties that have important characteristics for a range of possible end uses.

Whilst only British grown pines and poplar were shown to be suitable out of the range of species suggested for this study the investigation of other species should not be ruled out as it is possible other species not included in this study may prove suitable. Low density timber can be valued added to by the use of the Indurite treatment to meet a number of potential end uses but most will require attracting a high value end use to off set the processing costs required to carryout the treatment. There are potential uses that do not fall in to the high value added category that could benefit from such a treatment but the economics may mitigate against its use. Some potential end users are flooring, internal furniture and joinery, window joinery, external doors and trims and outdoor furniture. The involvement of Osmose can be seen as a positive development ensuring suitable market placement and appropriateness of treatments.


Date: 2005
Title: Obtaining better utilisation of UK grown small diameter oak & other hardwood stems using a novel sawing pattern for the production of structural members (223920)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
The principle objective of the project was to better utilise low value small diameter oak stems. In order to achieve the objective, the concept was devised whereby small diameter oak stems would be cut into four quarters, the edges machined and the sections bonded back together in a reverse orientation using a moisture insensitive adhesive. This would result in a square beam with a void running up the centre. The project has proven that the concept works very well. The process of constructing inside out beams in the ‘green’ state has been streamlined, and in theory, could easily be semi-automated.

It is recommended that the small oak stems be machine rounded to produce straight cylinders before any follow on process is attempted. This improves the process efficiency and allows the construction of standard beam dimensions from machine rounded stems. Four bonding edges are then planned on the stem prior to cutting into four sections, the sections are then spread with adhesive, turned inside out and pressed. The beams are then dried and planned to clean up any surface imperfections.
A number of work tasks were undertaken to assess various aspects of producing re-engineered oak stems and their physical properties. Assessments included:

1. Structural tests to ascertain strength characteristics
2. Assessments on suitable preservative or protective treatments to provide protection to the
    nondurable beam interior
3. Investigation on the distortional characteristics of different orientations of re-engineered
    components
4. Assessment of drying characteristics

Results from these assessments indicate that:

1. Re-engineered beams constructed from small oak stems (using the correct timber to void ratio) are
    both stronger and stiffer than solid oak beams processed from similar dimension material, and are
    comparable in strength and stiffness to solid beams processed from large diameter material.
2. Assessments on suitable preservative treatment indicate that it is possible to achieve complete
    preservative penetration of freshly constructed re-engineered beams using a boron diffusion
    process. Using the same process, it is also possible to provide a shallow envelope of protection on
    material which has already been partially dried.
3. The incidence of twist, bow & spring (after drying) is significantly reduced in re-engineered oak
    beams when compared to solid oak beams processed from the same material.
4. Drying assessments indicate that the re-engineered small oak stems exhibit significantly less
    surface checks and splits than solid material processed and dried at the same rate.

At the beginning of the project, there was a certain amount of scepticism whether the concept of bonding small diameter oak and other hardwood stems inside-out in the green state would be achievable. The project has been successful in proving the idea and the assessments on reengineered beams has all been extremely encouraging. Considering the amount of interest in the product from the wood industry and manufacturers, it is hope that after further investigation and assessment, the beams will be produced commercially sometime in the future.


Date: 2004
Title: Obtaining better utilisation of UK grown small diameter Oak stems and other hardwoods using a novel sawing pattern for the production of structural members
Authors: Report commissioned from BRE
Full report: PDF

Summary
This report presents the progress and results from the first of four work tasks in a series of eight, to utilise low value small oak stems and other hardwood species by using a novel cutting and jointing technique to produce re-engineered components. The project was funded by the Forestry Commission under contract number PPD 24/02, and is due to finish in September 2004.


Date: 2004
Title: Incising UK grown Sitka spruce (214436)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
Incising UK Sitka spruce for Hazard Class 4 applications may well offer process benefits as well as the product performance benefits. These might include the presence of incisions allowing more rapid drying and easier preservation treatment for UK grown Sitka spruce.

The aim of this project was to apply the results from previous research already undertaken at BRE as long term field trails and see if encouraging data could be generated for UK grown Sitka spruce.


Date: 2004
Title: Incised UK Sitka spruce – taking to market (233550)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
Incising UK Sitka spruce for Hazard Class 4 applications may well offer process benefits as well as the product performance benefits. These might include the presence of incisions allowing more rapid drying and easier preservation treatment for UK grown Sitka spruce.

The aim of this proposal is to apply the results from previous research already undertaken at BRE to optimise the incising process, the kiln drying schedule and preservative treatment schedule into the components of a realistic pilot scale operation. The project is organised into five principal tasks:

Task 1. Optimising tooth design for the incising head
Task 2. Optimising kiln drying schedule
Task 3. Optimising preservative treatment schedule
Task 4. Enabling market uptake and pilot scale production

Working in partnership with Arch Timber Protection data on potential for optimised treatment schedules is being investigated. Opportunities for accelerating kiln drying of incised timber appear to be limited.


Date: 2003
Title: UK Timber/Waste Plastic Composites (211511)
Authors: Report commissioned from BRE
Full Report: PDF
Update Report: PDF

Summary
This report details the results of a study into the potential of Wood Plastic Composites (WPCs*)  and the impact of these and other composite materials, such as Fibre Reinforced Polymerics (FRPs), on the UK forest products industry. This output represents the Review Report due March 2003 of project PPD27/02 full title "UK Timber/Waste Plastic Composites" The project objective is to investigate the potential of composites made from low grade or reject UK timber and post consumer plastic waste such as HDPE (high density polyethylene), together with structural reinforcement.

Although very much more low-tech compared with the more advanced FRPs, WPCs are beginning to be used for structural applications. Developments such afibre orientation and better coupling additives have already taken place. Although WPCs are generally weaker than timber, particularly in flexural stiffness, in many cases their structural performance will be adequate. The main advantage of WPCs is the resistance to decay, insect attack, warp and splintering.

Future development of WPCs for structural use may take the following form:

1. Co-extrusion with reinforcing rods (either steel or FRP)
2. Co-extrusion/pultrusion with longitudinal glass fibres (bundles, tapes or mats)
3. Modification of the thermoplastic/wood fibre mix into stiffer, more resin-like materials
4. Better bonding between matrix and fibre by advances in additive and cross-linking technologies
                                                 
The UK situation with respect to the supply of waste plastic and wood fibre poses no real problems for a potential UK wood plastic industry. WPCs require fine ground, dry, clean sources of wood fibre. This is most likely going to be obtained from the wood working industry rather than from sawmills or from virgin timber such as forest thinnings. Increased recycling of waste plastics and wood waste, and developments in production processes, will decrease the price of WPCs and encourage usage. Two WPC manufacturers have recently started production in the UK.

WPCs will displace use of solid timber in both outdoor and indoor markets. Advanced FRPs are an alternative to timber for some engineering applications such as bridges, but they are also beginning to be used for doors, window frames and cladding. Development of plastics and composites as wood-alternatives will have a negative affect on the potential for solid UK timber, in particular the development of "spruce for joinery".

Developmental research into WPCs as structural elements such as beams appears very worthwhile. However, FRPs offer much better structural performance with similar aesthetic appeal to waste plastic lumber. One of the primary reasons for choosing a timber (eg for a bridge) is the natural appearance.

* Note that "WPC" is also used as an abbreviation for Wood Polymer Composites.



Date: 2002
Title: Review of incising pre-treatment technology-potential for enhancing value of UK grown spruce (208080)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
The report presents a review of international literature and practical experience with incising refractory timber species prior to treatment with wood preservatives. The review presents the potential for applying incising technology to UK-grown Sitka spruce and provides recommendations for the way forward. The recommendations include:

1. Conduct of laboratory assessments of penetration and retention of CCA treated incise UK-grown
    spruce
2. Conduct of laboratory assessments of biological durability of CCA-treated incised and unincised
    spruce
3. Conduct of field assessments of biological durability of CCA-treated incised and unincised spruce,
    Douglas fir and larch.
4. Evaluation of the perception of incised material in the market place
5. Producing demonstration material from incised UK-grown Sitka spruce and put into test - including
    fencing, gates and cladding.
6. Developing a demonstration project within a specific commodity production chain including
    manufacturers, UK spruce growers, sawmills and end-users. 
7. Producing a guidance document on incising Sitka spruce to raise the profile of the technology in
    the UK

In addition the preservative treatment schedules, the kiln drying and the incising process would need to be optimised prior to the full-scale practical development of incising technology in the UK.


Date: 2002
Title: Green–gluing (PPD18, CV6322, PT1777)
Authors: Report commissioned from BRE
Full Report: Awaiting electronic version

Summary
This small resource was provided to organise and present a green gluing road show.  A lot of work had been done, and this event was used to disseminate the good news.  The full day event was held in the Midlands to an invited audience which comprised mainly of wood industry people.


Date: 2001
Title: Wet-glued products - evaluation of standards (204661)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This client report presents a review of how structural timber produced using ‘green (wet) gluing’ technology (GREENWELD and Collano polyurethane systems) can be successfully marketed. The effect of the current and planned regulatory framework (codes and standards) is assessed and the option for using third party certification is discussed. The work was jointly funded by the Forestry Commission’s Policy and Practice Division and the United Kingdom Forest Products Association. The review of current and future codes and standards has shown that the development of European standards is a long way behind the current developments in technology for green gluing. As a consequence, in the short-term it is believed that the only effective route to bringing green glued products, particularly those using polyurethane, to the market place is by third party accreditation. The long-term approach will be to ensure that relevant European standards currently under development allow the use of green gluing. BRE is actively working towards this through its participation in the relevant BSI and CEN committees and working groups.

The main difficulty concerning the UK and European standards route to the commercialisation of green gluing technology for structural products is that neither of the adhesives currently used have been formally evaluated for compliance to EN301. GREENWELD is a resorcinol based adhesive and thus comes under the remit of the standard when bonding dry timber. However, currently EN301 does not include provisions for testing polyurethane adhesives. In the future, the compliance of polyurethanes as structural adhesives by the European standards route is likely to be possible by the development of a new standard by TC 193/SC1/WG4 (the CEN wood adhesives committee’s Working Group for ‘NovelAdhesives’).

The current EN386 and draft prEN386 have a clause for strict limits on moisture content of the timber used for laminations and this is considerably below the moisture content desirable and cost effective for green gluing. The UK representatives on the CEN committee dealing with these documents need to ensure that the standards cover all the necessary performance criteria but are flexible and do not hinder new technologies, including the use of green gluing for structural  products.

The recommended short-term route for the commercialisation of the technology concerned with the wet gluing of timber is by third party certification and there are two stages to achieving this:

(a) Certification of the adhesive, using the testing regime of EN 301. This is expected to be organised by the adhesive manufacturer. Review of regulatory framework (codes and standards) in relation to the use of green glued structural timber.
(b) Certification of the specific products to show that their performance is adequate for their intended use (fit for purpose). This will be the responsibility of the users of the adhesive.

BRE has already carried out some components of the required resting but further work will be necessary. For some uses the additional testing will be considerable. However, for the certification of polyurethane as an adhesive suitable for structural use, it is anticipated that the results of third party certification testing from Germany, Sweden and France can be used as an example.